Heat assisted magnetic recording with an anisotropic heat sink

Abstract

A magnetic recording medium for heat assisted magnetic recording (HAMR) including in ascending vertical sequence: (i) a substrate; (ii) a first amorphous layer, a first seed layer, or a combination thereof; (iii) a heat sink layer comprising hexagonal boron-nitride grains; (iv) an optional second amorphous layer; (v) an optional second seed layer; (vi) a magnetic recording layer; (vii) an optional capping layer; and (viii) an optional overcoat layer; wherein: the magnetic recording medium has a substrate plane and a basal plane perpendicular to the substrate plane; the heat sink layer is anisotropic and has an a-axis thermal conductivity in the basal plane and a c-axis thermal conductivity in the substrate plane, wherein the a-axis thermal conductivity is greater than the c-axis thermal conductivity; and the hexagonal boron-nitride grains have an average size of at least about 10 nm in the substrate plane. Also, provided is a method of manufacturing the magnetic recording medium for HAMR.

What is claimed is: 
     
       1. A magnetic recording medium for heat assisted magnetic recording comprising in ascending vertical sequence:
 (i) a substrate; 
 (ii) a first amorphous layer, a first seed layer, or a combination thereof; 
 (iii) a heat sink layer comprising hexagonal boron-nitride grains; 
 (iv) an optional second amorphous layer; 
 (v) an optional second seed layer; 
 (vi) a magnetic recording layer; 
 (vii) an optional capping layer; and 
 (viii) an optional overcoat layer; 
 wherein:
 the magnetic recording medium has a substrate plane and a basal plane perpendicular to the substrate plane; 
 the heat sink layer is anisotropic and has an a-axis thermal conductivity in the basal plane and a c-axis thermal conductivity in the substrate plane, wherein the a-axis thermal conductivity is greater than the c-axis thermal conductivity; and 
 the hexagonal boron-nitride grains have an average size of at least about 10 nm in the substrate plane. 
 
 
     
     
       2. The magnetic recording medium of  claim 1 , wherein the hexagonal boron-nitride grains have an average size of about 10 nm to about 1000 nm in the substrate plane. 
     
     
       3. The magnetic recording medium of  claim 1 , wherein the hexagonal boron-nitride grains have an average size of about 50 nm to about 200 nm in the substrate plane. 
     
     
       4. The magnetic recording medium of  claim 1 , wherein the heat sink layer has a thermal conductivity of at least about 45 W/mK in the basal plane. 
     
     
       5. The magnetic recording medium of  claim 1 , wherein the heat sink layer has a thermal conductivity of about 45 W/mK to about 600 W/mK in the basal plane. 
     
     
       6. The magnetic recording medium of  claim 1 , wherein the heat sink layer has a thermal conductivity of no more than about 40 W/mK in the substrate plane. 
     
     
       7. The magnetic recording medium of  claim 1 , wherein the heat sink layer has a thickness of at least about 10 nm. 
     
     
       8. The magnetic recording medium of  claim 1  comprising the first seed layer, wherein the first seed layer comprises one or more crystalline layers. 
     
     
       9. The magnetic recording medium of  claim 8 , wherein the one or more crystalline layers comprises a hexagonal close packed (HCP) crystal structured layer, a body centered cubic (BCC) crystal structured layer, a B2 crystal structured layer, a B1 crystal structured layer, a spinel crystal structured layer, a perovskite crystal structured layer, or combinations of two or more thereof. 
     
     
       10. The magnetic recording medium of  claim 9 , wherein the first seed layer comprises the HCP crystal structured layer. 
     
     
       11. The magnetic recording medium of  claim 9 , wherein the first seed layer comprises the BCC crystal structured layer. 
     
     
       12. The magnetic recording medium of  claim 9 , wherein the first seed layer comprises the B2 crystal structured layer. 
     
     
       13. The magnetic recording medium of  claim 9 , wherein the first seed layer comprises the B1 crystal structured layer. 
     
     
       14. The magnetic recording medium of  claim 9 , wherein the first seed layer comprises the spinel crystal structured layer. 
     
     
       15. The magnetic recording medium of  claim 9 , wherein the first seed layer comprises the perovskite crystal structured layer. 
     
     
       16. The magnetic recording medium of  claim 1  comprising the first seed layer, wherein the first seed layer comprises a ceramic layer. 
     
     
       17. The magnetic recording medium of  claim 8  further comprising the first amorphous layer. 
     
     
       18. The magnetic recording medium of  claim 16  further comprising the first amorphous layer. 
     
     
       19. The magnetic recording medium of  claim 1  comprising the first amorphous layer. 
     
     
       20. A method of for manufacturing a magnetic recording medium for heat assisted magnetic recording comprising providing sequentially:
 (i) a substrate; 
 (ii) a first amorphous layer, a first seed layer, or a combination thereof; 
 (iii) a heat sink layer comprising hexagonal boron-nitride grains; 
 (iv) an optional second amorphous layer; 
 (v) an optional second seed layer; 
 (vi) a magnetic recording layer; 
 (vii) an optional capping layer; and 
 (viii) an optional overcoat layer; 
 wherein:
 the magnetic recording medium has a substrate plane and a basal plane perpendicular to the substrate plane; 
 the heat sink layer is anisotropic and has an a-axis thermal conductivity in the basal plane and a c-axis thermal conductivity in the substrate plane, wherein the a-axis thermal conductivity is greater than the c-axis thermal conductivity; and 
 the hexagonal boron-nitride grains have an average size of at least about 10 nm in the substrate plane.